Fisheries

Overfishing occurs when fish are caught at a rate higher than the population is able to replace itself. Collapse will ultimately occur if overfishing is prolonged over time. A government analysis indicates that 17.5% of Australian fish stocks are overfished or are being fished too heavily, and the status of 16.5% is not known.

Despite being almost endangered, it currently legal in Australia to commercially fish for school, scalloped hammerhead and gulper sharks, blue warehou, dogfish, orange roughy, eastern gemfish and southern bluefin tuna. All of these fish are categorised by government as ‘Conservation Dependent’, which is a category that acknowledges that these species are under threat from fishing, but can still be fished.

Bycatch is marine life that is killed or damaged during the fishing process but is not retained. Different methods of fishing have different levels of bycatch, and sometimes our most precious threatened species are accidentally caught and drowned in fishing nets. Seals are caught in nets trawling for fish. Dolphins, dugongs and Australian sea lions are caught and drowned in gillnets fishing for sharks. Sea turtles are caught on longlines fishing for tuna.

Some Australian fisheries are making great progress to reduce their bycatch impact on non target species, but we still have a long way to go.

A gillnet is a net that is hung vertically in the sea to entangle fish, but it is also invisible and deadly for our precious and endangered marine wildlife. There have been incidents of unique and rare snubfin dolphins drowned in legally set gillnets in the Great Barrier Reef Marine Park.

Dugongs and turtles have also been killed in gillnets in the Great Barrier Reef, so conservationists are now call for netting bans in high value dugong, dolphin and turtle habitats.

Gillnet fishing is more sustainable when nets are constantly attended, deployed in the water for only a short time, and not in areas that are habitats for vulnerable species. This can improve the survival of species not intended to be caught.

Longline fishing is a method where a fishing line kilometres long is set with thousands of baited hooks suspended in the water column or laid along the seabed, waiting for tuna, swordfish and sharks to bite. Longlines can kill turtles, sharks,whales, and seabirds seabirds every year, including endangered species such as the Wandering Albatross and vulnerable species such as the Grey-headed Albatross.

Longline fishing is more sustainable when fishing gear modifications are put in place to reduce the number of protected wildlife from being caught, and when important ocean habitats are protected in marine parks.

Aquaculture, or fish farming, is the process of raising fish in farms rather than catching them in the wild. It sounds good, but fish farms don’t necessarily reduce the pressure on wild populations. For example, for every kilogram of farmed Atlantic salmon produced in Australia, more wild fish is used as feed than is produced on the farm.

Aquaculture can also bring issues of pollution and habitat destruction in parts of our coast which are often used for farms.

Aquaculture is more sustainable when species are farmed (or are fed diets) that ensure less wild fish is required than is produced, and where careful and precautionary industry regulation ensures that waste effluent does not damage sensitive environments..